Revetment blocks are well known for preventing or controlling erosion in areas that carry runoff water. The blocks can be manually installed as a mat in the watershed areas, or installed as cabled mats in the areas to control the flow of water. The cabling of a mat of erosion control blocks is carried out by laying a mat of blocks on the ground or other suitable surface and extending cables through the cable channels of the blocks to effectively cable the entire group of blocks together as a unit. The unit or mat of blocks is then lifted by a crane via the cables and laid onto the watershed area to be protected from erosion. The installation of the cabled mat of erosion control blocks is advantageous where the area to be protected is covered with water. Once each cabled mat is lowered and installed in place, divers can be employed in deep water areas to attach the edges of the mats of blocks together to provide an overall integrity to the entire system of mats.
Erosion control blocks are available in many different designs, each to satisfy a particular need. When a large watershed area is to be protected by large mats of erosion control blocks, the project is usually placed up for bid to allow competitors to compete for the job according to stated specifications. The bid includes a number of specifications for the individual blocks as well as the arrangement when cabled together. Some bids require that the mat of blocks be cabled together in only one direction, and not in the orthogonal direction of the mat. Other bid specifications require that the mat of blocks be cabled together in both orthogonal directions. Yet other bid specifications require the erosion control blocks to be aligned together in a mat side-by-side in both rows and columns, such as shown in U.S. Pat. No. 5,484,230 by Rudloff. Other bid specifications require the erosion control blocks to be staggered in one direction, such as depicted in U.S. Pat. No. 4,370,075 by Scales.
Because of the individual design features of many erosion control blocks, a single type of block cannot often satisfy all of the bid specifications of different jobs or projects. A certain type of block can satisfy some job specifications, and other types of blocks can satisfy other job specifications. Thus, it has heretofore been difficult to achieve a block design that could satisfy many different job specifications and thus have universal applications in many different projects.
From the foregoing, a need exists for a revetment block that can be configured in either a mat of side-by-side blocks, or in a mat of staggered blocks. Another need exists for a revetment block that is registered in rows using guide ribs and guide slots, irrespective of whether the blocks are configured in the side-by-side arrangement or the staggered arrangement. Yet another need exists for a block where the cable exits one block and enters the neighbor block at a location adjacent a point or edge of articulation between the blocks to thereby facilitate articulation when suspended in a catenary.